A number of systems exist which provide both mobile terrestrial communication (ie., cellular communication) and mobile satellite communication between terminals. Such a system is hereinafter referred to as an MSAT system. Satellite communication between two terminals is typically implemented via a double-hop, that is, two signal paths. One signal path is from an originating terminal to a ground station via a satellite, and the other signal path is from the ground station to a destination terminal via the satellite. A single-hop, one-way propagation delay can occur which can be on the order of 270 milliseconds (ms). Thus, in a double-hop MSAT system, the propagation delay can be on the order of 540 ms, which can create unacceptable interruptions during calls, particularly voice calls.
A number of single-hop MSAT systems exist; however, these single-hop systems are disadvantageous because signaling paths are terminated once a single-hop satellite signal path is established for a call between two terminals. Without a signaling path during the terminal-to-terminal (TtT) call, no services such as ciphering key exchanges for encryption can be offered within the MSAT system. Thus, callers cannot be guaranteed their privacy during calls within the single-hop MSAT system. A need therefore exists for a single-hop MSAT system which maintains a signaling path during a TtT call for services such ciphering for privacy, among others.